Art of refining kaolin and similar clays for use in making pottery and like products.



v :UNITED STATES PATENT onnrcn.

WILLIAM. w. smonso'n, or CINCINNATI, OHIO.

ART. OF REFINING KAOLIN' AND SIMILAR CLAYS FOR USE IN' MAKING' PdT'IER-Y LIKE PRODUCTS.

Be it known that I, WILLIAM W. SiMoN- son, a c1t1zen ofthe United States of Amer- .i-ca, and a resident of Cincinnati, in the county of Hamilton and State of Ohio, have invented a certain new and-useful Improvement in the Artof Refining Kaolin and Similar Clays for Use in Making Pottery and like Products, of which the following is a specification.

This invention relates to the process of decolorizing kaolin, bauxite, barite and allied materials that are used more particularly in the manufacture of white chinaware. a The principal objectof the process herein is the removal of iron, such as oxid, or as hydrated oxid, from potters clays in a simple, eflicient, expeditious and economical manner, and without any material detriment or injury to the clay itself or to the ware manufactured therefrom.

A very material object of the invention herein is the ready utilization of the hitherto wasted already-mined kaolin or clay that has been neglected and cast aside, adjacent the mine or bank deposits where it was but very poorly refined and with a loss of at least 85% of the original raw inaterialtakenfrom the mine or bank. It is well known to I the art that immense quantities of said poorly or deficiently refined kaolin or clayare already lying broadcast andunused and awaiting just such a process as .the 'one herein to utilize or redeem them and to purge them of color and impurities and so that the actual residue-waste shall be practically m'l or imperceptible. Thus, the labor required in actually mining the kaolin or clay is materially lessened and saved, the unworked raw material or deposits in the mine or bank being really unnecessary to disturb for a long time to come and only after said already-mined but defectively refined material is exhausted.

It is a well-known fact that the processes heretofore used and extant for removing iron-oxid from variqus clays involve the reduction of the ferric compounds to soluble ferrous-salts and thatthe general or principal reducing agent has been sulfur-dioxid that becomes sulfuric-acid, or ferrous-sulfate combination simultaneously. ,Such reaction is exceedingly tardy and slow in cases of primary clays used, and still slower Specification of Letters Patent; I

is in an insolublestate.

this insoluble copper may be disregarded if' i Patented May 30, 1916.

Application filed bctober 20, 1915. Serial No.- 57,015.

in cases of most of the secondary clays-and,

in fact, is never really complete within the time-limits allowed for anysuccessful and profitable industrial application.

.The invention herein, therefore, contemplates the hastening or speeding of the reaction between iron-oxid'and sulfurous-acid,

which I have found in practice can be successfully accomplished by the employment I v of a small proportion of copper, the, latter bemg added as a soluble salt, either cupric or cuprous. In actual use by me, cupricsulfate 1s employed, although, under certain conditions, the use of cupous-chlorid can be of greater advantage although not essential. Now, however, whether beginning with a cuprlc salt or a cuprous salt, the end or termination of the solution of the iron-oxid finds most of the copper in solution as a cupric-salt, but always witha part present as a cuprous-salt, a portion 'of which latter Relatively small,

the clay is to be used for facing paper or for other purely mechanical purposes, but it may not remain in the clay if the same is to be used in the potters mixtures. In order to remove this copper that is retained or held insoluble by the clay, an-oxidizing agent must be used and preferably in an acid bath, whereby this copper becomes dissolved as a cupric-salt and is afterward removed in a subsequent washing of the purified or-refined clay with water.

The state of combination of the retained copper is not known to a certainty, it amounting, however, topra'ctically one part copper in fivethousand of clay and as little as one part copper to twenty-five thousand of-clay. It is known, too, that thiscopper should not reach the pottery mixtures and that chlorin removes it from the clay, always as a cupric-salt (chlorid).

It will be observed that, at will, the products ofthereaction, soluble after the iron has been dissolved, may be readily washed away from the clay, and the insoluble cuprous salt then oxidized and washed away, while the cuprous salt itself may be oxidized in the presence, of the soluble ferrous-salts, and then the total metallic salts removed by a single washing. In either case, however, after the entire bulk of the soluble material has been washed away or removed by the use of water, the partly washed clay is to be given a wash of dilute acid and water, and

this acid-wash then goes into the prepara tion of the next-acid-bath that is to be used on a later or succeeding quantity of clay. This acid-bath is very material and useful in the process herein in order to fully avoid the retention by the clay of any part of the iron as a basic compound. Upon further washing with water, until the successive washings shall give no response with testing re-agents for iron, the clay can be dried Without disclosing or showing any stain or color on the surface of the dried cakes or masses thereof. It will be observed, at this point, that the most convenient and best oxidizer for converting cuprous salts to cupric salts in thisprocess is chlorin, which is preferably added as a gas to the aforesaid dilute acid-bath, in which latter the iron-free clay is suspended.

The following formula for the iron-removing bath is one of the many possible ones that I claim as embodying my invention herein, the amount of copper employed being suflicient for practical and rapid work, a much less amount of copper not being practical nor useful, and a very material or greatly increased amount being really unnecessary Kaolin 2000 pounds avoirdupois Sulfuric-acid, 77%

or 60 Ba'um 40 J Sulfur-dioxid 12 Cupric-sulfate 2 g Water 5000 The mass of-clay is first mixed with the 'water' until a smooth slip is obtained, the

' riod of about four hours at the most. The

proportions of the said three re-agents of this formula can be variedto a considerable extent, those above-given applying to very badly or strongly colored clays and to a dissolving-period of about four hours time that is to be considered as very rapid in the light of the many days time heretofore required in producing even an inferior result,

' without the copper and bath, with the product still retaining a trace or hue of the iron color therein, and which is not true of the product resulting from my process herein.

The detail of washing the iron-free clay, and of acting upon it with chlorin, or with an equivalent of chlorin, may be considerably varied, as previously described.

I have further found that cuprous -chlorid can be recovered from low-grade copper ores by the well-known Hunt and Douglas process, in which case the action of sulfurdioxid precedes entirely the action of the cuprous-salt on the ferric compounds of the clays instead of going on concurrently with it. In the example of the iron-removing bath'previously given, 40 to 50 pounds of dry cuprous-chlorid would be used instead of the cupric-sulfate and sulfur-dioxid.

I claim 1. The process of removing iron from clays, consisting in the employment of a solvent containing dilute acid and a cuprous salt.

2. The process of removing iron from solvent containing dilute sulfuric-acid, sulfurous-acid and a salt of copper soluble in an acid solution. v

3. In the process of removing iron from clays, the use of salts of copper for hastening the reaction occurring between sulfurous-acid and iron compounds contained in said clays.

4. In the process of removing iron from clays, the combined action of an acid, asalt of copper and a reducing agent able to convert ferric compounds to ferrous compounds.

'5. The process of removing iron from clays, consisting in the employment of a v solvent containing dilute sulfuric-acid and cuprous-chlorid.

6. 'As an improvement in the art of refining kaolin for use in making pottery and like products, the hereindescribed process ofremoving iron compounds from said kaolin consisting in the joint-action of an acid, a soluble salt of copper and a reducing agent for converting ferric-oxid to ferrous oxid or salt.

7. The process of refining kaolin and similar clays for use in making white-ware and like pottery-products consisting in the employment of soluble copper salts for speeding or hastening the reaction that 00- curs between sulfurous-acid and ferric-oxid or hydrated, insoluble ferric compounds existing or occurring in said clays.

8. The process of removing iron from kaolin or like clay material in the purisoluble in an acid solution.

9. The process of removing iron from clays and like clay materials, consisting in acting upon the clay with a bath containing a mineral-acid, sulfurous-acid and a salt of copper, heated. below the boiling-point of the bath until suflicient of the iron has been dissolved, then adding chlorin in excess of that taken up by the sulfur-dioxid and the cuprous and ferrous salts, and then Washing the purified clay practically free from soluble compounds.

, 10. The process of removing iron from clays and like clay materials consisting in acting upon the clay with a bath containing a mineral-acid and a cuprous salt, heated belowthe boiling-point of the bath until suflicient of the 'iron has been dissolved, adding chlorin in excess of that/taken up by the ferrous and cuprous salts, and then washing the purified clay practically free from soluble compounds.

11-. The process of removing iron compounds from kaolin and other like clays for use in the manufacture of White pottery-I products consisting in treating the clay with a bath containing sulfuric-acid, sulfurousacid and a copper salt, such bath being heated below its boiling-point, then removing the dissolved iron salts and the accompanying re-agents, and then treating the partially purified clay with a dilute acid, and with chlorin sufiicient tobe in excess of that used in the conversion of cuprous salt to cupric salt, and finally Washing the refined clay so that it shall be practically free from soluble compounds.

12. The process of removing iron from kaolin and other like clays used in the manufacture of chinaware or white potteryproducts consisting in washing the clay in a'bath of a mineral-acid, sulfurous-acid and a copper salt, the same being heated ,below its boiling-point until the iron has been dissolved therein, then adding chlorin in excess of that taken up by cuprous and ferrous salts, and then washing the purified.

clay until practically free from all soluble compounds.

13. The process of removing iron from clays and like clay materials, consisting in acting upon the clay with a bath containin dilute sulfuric-acid and cuprous chlori heated below the boiling-point of the bath, then removingthe dissolved iron and copper and the accompanying re-agents of the bath and treating the partially purified clay with dilute-acid and chlorin in excess of that taken up by the cuprous compound retainedby the clay, and then washing therefined clay practically free from soluble compounds. 4

WILLIAM W. SIMONSON.

Witnesses: JOHN ELIAS JONES.

BERL B. RmnoN. 

